The effect of the surface energy and structure of the SiC substrate on epitaxial graphene growth
The exposed surfaces of the SiC substrate have a great influence on the epitaxial graphene growth and morphology and thus influence the properties of graphene-based microelectronic devices. In this work, the surface structures of the SiC substrate were determined by first principle theoretical calculations. Calculated surface energies suggested that the SiC step structure, forming on the H2 etching procedure, would be reconstructed and self-ordering to expose the (1−106) facet. The inclined angle of 33.23° of the vicinal surface observed by Atomic Force Microscope (AFM) demonstrated the calculated results. The relationship between graphene growth and the surface Si–C bonding strength was revealed by calculating the formation energies of Si vacancies. Combined the calculated formation energies with Raman analysis, we concluded that the nucleation of graphene growth on the SiC substrate preferred to occur at step (1−106) surface rather than terrace (0001) surface. In addition, the single Si atom would facilitate the assembling of surface C atoms. The present theoretical and experimental work is helpful to optimize the technology of epitaxial graphene growth on the SiC substrate.